xref: /freebsd/lib/libthr/thread/thr_init.c (revision e1fe3dba5ce2826061f6489765be9b4a341736a9)
1 /*
2  * Copyright (c) 2003 Daniel M. Eischen <deischen@freebsd.org>
3  * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. All advertising materials mentioning features or use of this software
15  *    must display the following acknowledgement:
16  *	This product includes software developed by John Birrell.
17  * 4. Neither the name of the author nor the names of any co-contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * $FreeBSD$
34  */
35 
36 #include "namespace.h"
37 #include <sys/types.h>
38 #include <sys/signalvar.h>
39 #include <sys/ioctl.h>
40 #include <sys/sysctl.h>
41 #include <sys/ttycom.h>
42 #include <sys/mman.h>
43 #include <errno.h>
44 #include <fcntl.h>
45 #include <paths.h>
46 #include <pthread.h>
47 #include <pthread_np.h>
48 #include <signal.h>
49 #include <stdlib.h>
50 #include <string.h>
51 #include <time.h>
52 #include <unistd.h>
53 #include "un-namespace.h"
54 
55 #include "libc_private.h"
56 #include "thr_private.h"
57 
58 void		*_usrstack;
59 struct pthread	*_thr_initial;
60 int		_thr_scope_system;
61 int		_libthr_debug;
62 int		_thread_event_mask;
63 struct pthread	*_thread_last_event;
64 pthreadlist	_thread_list = TAILQ_HEAD_INITIALIZER(_thread_list);
65 pthreadlist 	_thread_gc_list = TAILQ_HEAD_INITIALIZER(_thread_gc_list);
66 int		_thread_active_threads = 1;
67 atfork_head	_thr_atfork_list = TAILQ_HEAD_INITIALIZER(_thr_atfork_list);
68 umtx_t		_thr_atfork_lock;
69 
70 struct pthread_attr _pthread_attr_default = {
71 	.sched_policy = SCHED_RR,
72 	.sched_inherit = 0,
73 	.sched_interval = TIMESLICE_USEC,
74 	.prio = THR_DEFAULT_PRIORITY,
75 	.suspend = THR_CREATE_RUNNING,
76 	.flags = 0,
77 	.arg_attr = NULL,
78 	.cleanup_attr = NULL,
79 	.stackaddr_attr = NULL,
80 	.stacksize_attr = THR_STACK_DEFAULT,
81 	.guardsize_attr = 0
82 };
83 
84 struct pthread_mutex_attr _pthread_mutexattr_default = {
85 	.m_type = PTHREAD_MUTEX_DEFAULT,
86 	.m_protocol = PTHREAD_PRIO_NONE,
87 	.m_ceiling = 0,
88 	.m_flags = 0
89 };
90 
91 /* Default condition variable attributes: */
92 struct pthread_cond_attr _pthread_condattr_default = {
93 	.c_pshared = PTHREAD_PROCESS_PRIVATE,
94 	.c_clockid = CLOCK_REALTIME
95 };
96 
97 pid_t		_thr_pid;
98 int		_thr_guard_default;
99 int		_thr_stack_default = THR_STACK_DEFAULT;
100 int		_thr_stack_initial = THR_STACK_INITIAL;
101 int		_thr_page_size;
102 int		_gc_count;
103 umtx_t		_mutex_static_lock;
104 umtx_t		_cond_static_lock;
105 umtx_t		_rwlock_static_lock;
106 umtx_t		_keytable_lock;
107 umtx_t		_thr_list_lock;
108 umtx_t		_thr_event_lock;
109 
110 int	__pthread_cond_wait(pthread_cond_t *, pthread_mutex_t *);
111 int	__pthread_mutex_lock(pthread_mutex_t *);
112 int	__pthread_mutex_trylock(pthread_mutex_t *);
113 void	_thread_init_hack(void) __attribute__ ((constructor));
114 
115 static void init_private(void);
116 static void init_main_thread(struct pthread *thread);
117 
118 /*
119  * All weak references used within libc should be in this table.
120  * This is so that static libraries will work.
121  */
122 STATIC_LIB_REQUIRE(_accept);
123 STATIC_LIB_REQUIRE(_bind);
124 STATIC_LIB_REQUIRE(_close);
125 STATIC_LIB_REQUIRE(_connect);
126 STATIC_LIB_REQUIRE(_dup);
127 STATIC_LIB_REQUIRE(_dup2);
128 STATIC_LIB_REQUIRE(_execve);
129 STATIC_LIB_REQUIRE(_fcntl);
130 STATIC_LIB_REQUIRE(_flock);
131 STATIC_LIB_REQUIRE(_flockfile);
132 STATIC_LIB_REQUIRE(_fstat);
133 STATIC_LIB_REQUIRE(_fstatfs);
134 STATIC_LIB_REQUIRE(_fsync);
135 STATIC_LIB_REQUIRE(_getdirentries);
136 STATIC_LIB_REQUIRE(_getlogin);
137 STATIC_LIB_REQUIRE(_getpeername);
138 STATIC_LIB_REQUIRE(_getsockname);
139 STATIC_LIB_REQUIRE(_getsockopt);
140 STATIC_LIB_REQUIRE(_ioctl);
141 STATIC_LIB_REQUIRE(_kevent);
142 STATIC_LIB_REQUIRE(_listen);
143 STATIC_LIB_REQUIRE(_nanosleep);
144 STATIC_LIB_REQUIRE(_open);
145 STATIC_LIB_REQUIRE(_pthread_getspecific);
146 STATIC_LIB_REQUIRE(_pthread_key_create);
147 STATIC_LIB_REQUIRE(_pthread_key_delete);
148 STATIC_LIB_REQUIRE(_pthread_mutex_destroy);
149 STATIC_LIB_REQUIRE(_pthread_mutex_init);
150 STATIC_LIB_REQUIRE(_pthread_mutex_lock);
151 STATIC_LIB_REQUIRE(_pthread_mutex_trylock);
152 STATIC_LIB_REQUIRE(_pthread_mutex_unlock);
153 STATIC_LIB_REQUIRE(_pthread_mutexattr_init);
154 STATIC_LIB_REQUIRE(_pthread_mutexattr_destroy);
155 STATIC_LIB_REQUIRE(_pthread_mutexattr_settype);
156 STATIC_LIB_REQUIRE(_pthread_once);
157 STATIC_LIB_REQUIRE(_pthread_setspecific);
158 STATIC_LIB_REQUIRE(_read);
159 STATIC_LIB_REQUIRE(_readv);
160 STATIC_LIB_REQUIRE(_recvfrom);
161 STATIC_LIB_REQUIRE(_recvmsg);
162 STATIC_LIB_REQUIRE(_select);
163 STATIC_LIB_REQUIRE(_sendmsg);
164 STATIC_LIB_REQUIRE(_sendto);
165 STATIC_LIB_REQUIRE(_setsockopt);
166 STATIC_LIB_REQUIRE(_sigaction);
167 STATIC_LIB_REQUIRE(_sigprocmask);
168 STATIC_LIB_REQUIRE(_sigsuspend);
169 STATIC_LIB_REQUIRE(_socket);
170 STATIC_LIB_REQUIRE(_socketpair);
171 STATIC_LIB_REQUIRE(_thread_init_hack);
172 STATIC_LIB_REQUIRE(_wait4);
173 STATIC_LIB_REQUIRE(_write);
174 STATIC_LIB_REQUIRE(_writev);
175 
176 /*
177  * These are needed when linking statically.  All references within
178  * libgcc (and in the future libc) to these routines are weak, but
179  * if they are not (strongly) referenced by the application or other
180  * libraries, then the actual functions will not be loaded.
181  */
182 STATIC_LIB_REQUIRE(_pthread_once);
183 STATIC_LIB_REQUIRE(_pthread_key_create);
184 STATIC_LIB_REQUIRE(_pthread_key_delete);
185 STATIC_LIB_REQUIRE(_pthread_getspecific);
186 STATIC_LIB_REQUIRE(_pthread_setspecific);
187 STATIC_LIB_REQUIRE(_pthread_mutex_init);
188 STATIC_LIB_REQUIRE(_pthread_mutex_destroy);
189 STATIC_LIB_REQUIRE(_pthread_mutex_lock);
190 STATIC_LIB_REQUIRE(_pthread_mutex_trylock);
191 STATIC_LIB_REQUIRE(_pthread_mutex_unlock);
192 STATIC_LIB_REQUIRE(_pthread_create);
193 
194 /* Pull in all symbols required by libthread_db */
195 STATIC_LIB_REQUIRE(_thread_state_running);
196 
197 #define	DUAL_ENTRY(entry)	\
198 	(pthread_func_t)entry, (pthread_func_t)entry
199 
200 static pthread_func_t jmp_table[][2] = {
201 	{DUAL_ENTRY(_pthread_atfork)},	/* PJT_ATFORK */
202 	{DUAL_ENTRY(_pthread_attr_destroy)},	/* PJT_ATTR_DESTROY */
203 	{DUAL_ENTRY(_pthread_attr_getdetachstate)},	/* PJT_ATTR_GETDETACHSTATE */
204 	{DUAL_ENTRY(_pthread_attr_getguardsize)},	/* PJT_ATTR_GETGUARDSIZE */
205 	{DUAL_ENTRY(_pthread_attr_getinheritsched)},	/* PJT_ATTR_GETINHERITSCHED */
206 	{DUAL_ENTRY(_pthread_attr_getschedparam)},	/* PJT_ATTR_GETSCHEDPARAM */
207 	{DUAL_ENTRY(_pthread_attr_getschedpolicy)},	/* PJT_ATTR_GETSCHEDPOLICY */
208 	{DUAL_ENTRY(_pthread_attr_getscope)},	/* PJT_ATTR_GETSCOPE */
209 	{DUAL_ENTRY(_pthread_attr_getstackaddr)},	/* PJT_ATTR_GETSTACKADDR */
210 	{DUAL_ENTRY(_pthread_attr_getstacksize)},	/* PJT_ATTR_GETSTACKSIZE */
211 	{DUAL_ENTRY(_pthread_attr_init)},	/* PJT_ATTR_INIT */
212 	{DUAL_ENTRY(_pthread_attr_setdetachstate)},	/* PJT_ATTR_SETDETACHSTATE */
213 	{DUAL_ENTRY(_pthread_attr_setguardsize)},	/* PJT_ATTR_SETGUARDSIZE */
214 	{DUAL_ENTRY(_pthread_attr_setinheritsched)},	/* PJT_ATTR_SETINHERITSCHED */
215 	{DUAL_ENTRY(_pthread_attr_setschedparam)},	/* PJT_ATTR_SETSCHEDPARAM */
216 	{DUAL_ENTRY(_pthread_attr_setschedpolicy)},	/* PJT_ATTR_SETSCHEDPOLICY */
217 	{DUAL_ENTRY(_pthread_attr_setscope)},	/* PJT_ATTR_SETSCOPE */
218 	{DUAL_ENTRY(_pthread_attr_setstackaddr)},	/* PJT_ATTR_SETSTACKADDR */
219 	{DUAL_ENTRY(_pthread_attr_setstacksize)},	/* PJT_ATTR_SETSTACKSIZE */
220 	{DUAL_ENTRY(_pthread_cancel)},	/* PJT_CANCEL */
221 	{DUAL_ENTRY(_pthread_cleanup_pop)},	/* PJT_CLEANUP_POP */
222 	{DUAL_ENTRY(_pthread_cleanup_push)},	/* PJT_CLEANUP_PUSH */
223 	{DUAL_ENTRY(_pthread_cond_broadcast)},	/* PJT_COND_BROADCAST */
224 	{DUAL_ENTRY(_pthread_cond_destroy)},	/* PJT_COND_DESTROY */
225 	{DUAL_ENTRY(_pthread_cond_init)},	/* PJT_COND_INIT */
226 	{DUAL_ENTRY(_pthread_cond_signal)},	/* PJT_COND_SIGNAL */
227 	{DUAL_ENTRY(_pthread_cond_timedwait)},	/* PJT_COND_TIMEDWAIT */
228 	{(pthread_func_t)__pthread_cond_wait,
229 	 (pthread_func_t)_pthread_cond_wait},	/* PJT_COND_WAIT */
230 	{DUAL_ENTRY(_pthread_detach)},	/* PJT_DETACH */
231 	{DUAL_ENTRY(_pthread_equal)},	/* PJT_EQUAL */
232 	{DUAL_ENTRY(_pthread_exit)},	/* PJT_EXIT */
233 	{DUAL_ENTRY(_pthread_getspecific)},	/* PJT_GETSPECIFIC */
234 	{DUAL_ENTRY(_pthread_join)},	/* PJT_JOIN */
235 	{DUAL_ENTRY(_pthread_key_create)},	/* PJT_KEY_CREATE */
236 	{DUAL_ENTRY(_pthread_key_delete)},	/* PJT_KEY_DELETE*/
237 	{DUAL_ENTRY(_pthread_kill)},	/* PJT_KILL */
238 	{DUAL_ENTRY(_pthread_main_np)},		/* PJT_MAIN_NP */
239 	{DUAL_ENTRY(_pthread_mutexattr_destroy)}, /* PJT_MUTEXATTR_DESTROY */
240 	{DUAL_ENTRY(_pthread_mutexattr_init)},	/* PJT_MUTEXATTR_INIT */
241 	{DUAL_ENTRY(_pthread_mutexattr_settype)}, /* PJT_MUTEXATTR_SETTYPE */
242 	{DUAL_ENTRY(_pthread_mutex_destroy)},	/* PJT_MUTEX_DESTROY */
243 	{DUAL_ENTRY(_pthread_mutex_init)},	/* PJT_MUTEX_INIT */
244 	{(pthread_func_t)__pthread_mutex_lock,
245 	 (pthread_func_t)_pthread_mutex_lock},	/* PJT_MUTEX_LOCK */
246 	{(pthread_func_t)__pthread_mutex_trylock,
247 	 (pthread_func_t)_pthread_mutex_trylock},/* PJT_MUTEX_TRYLOCK */
248 	{DUAL_ENTRY(_pthread_mutex_unlock)},	/* PJT_MUTEX_UNLOCK */
249 	{DUAL_ENTRY(_pthread_once)},		/* PJT_ONCE */
250 	{DUAL_ENTRY(_pthread_rwlock_destroy)},	/* PJT_RWLOCK_DESTROY */
251 	{DUAL_ENTRY(_pthread_rwlock_init)},	/* PJT_RWLOCK_INIT */
252 	{DUAL_ENTRY(_pthread_rwlock_rdlock)},	/* PJT_RWLOCK_RDLOCK */
253 	{DUAL_ENTRY(_pthread_rwlock_tryrdlock)},/* PJT_RWLOCK_TRYRDLOCK */
254 	{DUAL_ENTRY(_pthread_rwlock_trywrlock)},/* PJT_RWLOCK_TRYWRLOCK */
255 	{DUAL_ENTRY(_pthread_rwlock_unlock)},	/* PJT_RWLOCK_UNLOCK */
256 	{DUAL_ENTRY(_pthread_rwlock_wrlock)},	/* PJT_RWLOCK_WRLOCK */
257 	{DUAL_ENTRY(_pthread_self)},		/* PJT_SELF */
258 	{DUAL_ENTRY(_pthread_setcancelstate)},	/* PJT_SETCANCELSTATE */
259 	{DUAL_ENTRY(_pthread_setcanceltype)},	/* PJT_SETCANCELTYPE */
260 	{DUAL_ENTRY(_pthread_setspecific)},	/* PJT_SETSPECIFIC */
261 	{DUAL_ENTRY(_pthread_sigmask)},		/* PJT_SIGMASK */
262 	{DUAL_ENTRY(_pthread_testcancel)}	/* PJT_TESTCANCEL */
263 };
264 
265 static int init_once = 0;
266 
267 /*
268  * For the shared version of the threads library, the above is sufficient.
269  * But for the archive version of the library, we need a little bit more.
270  * Namely, we must arrange for this particular module to be pulled in from
271  * the archive library at link time.  To accomplish that, we define and
272  * initialize a variable, "_thread_autoinit_dummy_decl".  This variable is
273  * referenced (as an extern) from libc/stdlib/exit.c. This will always
274  * create a need for this module, ensuring that it is present in the
275  * executable.
276  */
277 extern int _thread_autoinit_dummy_decl;
278 int _thread_autoinit_dummy_decl = 0;
279 
280 void
281 _thread_init_hack(void)
282 {
283 
284 	_libpthread_init(NULL);
285 }
286 
287 
288 /*
289  * Threaded process initialization.
290  *
291  * This is only called under two conditions:
292  *
293  *   1) Some thread routines have detected that the library hasn't yet
294  *      been initialized (_thr_initial == NULL && curthread == NULL), or
295  *
296  *   2) An explicit call to reinitialize after a fork (indicated
297  *      by curthread != NULL)
298  */
299 void
300 _libpthread_init(struct pthread *curthread)
301 {
302 	int fd, first = 0;
303 	sigset_t sigset, oldset;
304 
305 	/* Check if this function has already been called: */
306 	if ((_thr_initial != NULL) && (curthread == NULL))
307 		/* Only initialize the threaded application once. */
308 		return;
309 
310 	/*
311 	 * Check the size of the jump table to make sure it is preset
312 	 * with the correct number of entries.
313 	 */
314 	if (sizeof(jmp_table) != (sizeof(pthread_func_t) * PJT_MAX * 2))
315 		PANIC("Thread jump table not properly initialized");
316 	memcpy(__thr_jtable, jmp_table, sizeof(jmp_table));
317 
318 	/*
319 	 * Check for the special case of this process running as
320 	 * or in place of init as pid = 1:
321 	 */
322 	if ((_thr_pid = getpid()) == 1) {
323 		/*
324 		 * Setup a new session for this process which is
325 		 * assumed to be running as root.
326 		 */
327 		if (setsid() == -1)
328 			PANIC("Can't set session ID");
329 		if (revoke(_PATH_CONSOLE) != 0)
330 			PANIC("Can't revoke console");
331 		if ((fd = __sys_open(_PATH_CONSOLE, O_RDWR)) < 0)
332 			PANIC("Can't open console");
333 		if (setlogin("root") == -1)
334 			PANIC("Can't set login to root");
335 		if (__sys_ioctl(fd, TIOCSCTTY, (char *) NULL) == -1)
336 			PANIC("Can't set controlling terminal");
337 	}
338 
339 	/* Initialize pthread private data. */
340 	init_private();
341 
342 	/* Set the initial thread. */
343 	if (curthread == NULL) {
344 		first = 1;
345 		/* Create and initialize the initial thread. */
346 		curthread = _thr_alloc(NULL);
347 		if (curthread == NULL)
348 			PANIC("Can't allocate initial thread");
349 		init_main_thread(curthread);
350 	}
351 	/*
352 	 * Add the thread to the thread list queue.
353 	 */
354 	THR_LIST_ADD(curthread);
355 	_thread_active_threads = 1;
356 
357 	/* Setup the thread specific data */
358 	_tcb_set(curthread->tcb);
359 
360 	if (first) {
361 		SIGFILLSET(sigset);
362 		SIGDELSET(sigset, SIGTRAP);
363 		__sys_sigprocmask(SIG_SETMASK, &sigset, &oldset);
364 		_thr_signal_init();
365 		_thr_initial = curthread;
366 		SIGDELSET(oldset, SIGCANCEL);
367 		__sys_sigprocmask(SIG_SETMASK, &oldset, NULL);
368 		if (_thread_event_mask & TD_CREATE)
369 			_thr_report_creation(curthread, curthread);
370 	}
371 }
372 
373 /*
374  * This function and pthread_create() do a lot of the same things.
375  * It'd be nice to consolidate the common stuff in one place.
376  */
377 static void
378 init_main_thread(struct pthread *thread)
379 {
380 	/* Setup the thread attributes. */
381 	thr_self(&thread->tid);
382 	thread->attr = _pthread_attr_default;
383 	/*
384 	 * Set up the thread stack.
385 	 *
386 	 * Create a red zone below the main stack.  All other stacks
387 	 * are constrained to a maximum size by the parameters
388 	 * passed to mmap(), but this stack is only limited by
389 	 * resource limits, so this stack needs an explicitly mapped
390 	 * red zone to protect the thread stack that is just beyond.
391 	 */
392 	if (mmap((void *)_usrstack - _thr_stack_initial -
393 	    _thr_guard_default, _thr_guard_default, 0, MAP_ANON,
394 	    -1, 0) == MAP_FAILED)
395 		PANIC("Cannot allocate red zone for initial thread");
396 
397 	/*
398 	 * Mark the stack as an application supplied stack so that it
399 	 * isn't deallocated.
400 	 *
401 	 * XXX - I'm not sure it would hurt anything to deallocate
402 	 *       the main thread stack because deallocation doesn't
403 	 *       actually free() it; it just puts it in the free
404 	 *       stack queue for later reuse.
405 	 */
406 	thread->attr.stackaddr_attr = (void *)_usrstack - _thr_stack_initial;
407 	thread->attr.stacksize_attr = _thr_stack_initial;
408 	thread->attr.guardsize_attr = _thr_guard_default;
409 	thread->attr.flags |= THR_STACK_USER;
410 
411 	/*
412 	 * Write a magic value to the thread structure
413 	 * to help identify valid ones:
414 	 */
415 	thread->magic = THR_MAGIC;
416 
417 	thread->cancelflags = PTHREAD_CANCEL_ENABLE | PTHREAD_CANCEL_DEFERRED;
418 	thr_set_name(thread->tid, "initial thread");
419 
420 	/* Default the priority of the initial thread: */
421 	thread->base_priority = THR_DEFAULT_PRIORITY;
422 	thread->active_priority = THR_DEFAULT_PRIORITY;
423 	thread->inherited_priority = 0;
424 
425 	/* Initialize the mutex queue: */
426 	TAILQ_INIT(&thread->mutexq);
427 	TAILQ_INIT(&thread->pri_mutexq);
428 
429 	thread->state = PS_RUNNING;
430 
431 	/* Others cleared to zero by thr_alloc() */
432 }
433 
434 static void
435 init_private(void)
436 {
437 	size_t len;
438 	int mib[2];
439 
440 	_thr_umtx_init(&_mutex_static_lock);
441 	_thr_umtx_init(&_cond_static_lock);
442 	_thr_umtx_init(&_rwlock_static_lock);
443 	_thr_umtx_init(&_keytable_lock);
444 	_thr_umtx_init(&_thr_atfork_lock);
445 	_thr_umtx_init(&_thr_event_lock);
446 	_thr_once_init();
447 	_thr_spinlock_init();
448 	_thr_list_init();
449 
450 	/*
451 	 * Avoid reinitializing some things if they don't need to be,
452 	 * e.g. after a fork().
453 	 */
454 	if (init_once == 0) {
455 		/* Find the stack top */
456 		mib[0] = CTL_KERN;
457 		mib[1] = KERN_USRSTACK;
458 		len = sizeof (_usrstack);
459 		if (sysctl(mib, 2, &_usrstack, &len, NULL, 0) == -1)
460 			PANIC("Cannot get kern.usrstack from sysctl");
461 		_thr_page_size = getpagesize();
462 		_thr_guard_default = _thr_page_size;
463 		_pthread_attr_default.guardsize_attr = _thr_guard_default;
464 		_pthread_attr_default.stacksize_attr = _thr_stack_default;
465 
466 		TAILQ_INIT(&_thr_atfork_list);
467 #ifdef SYSTEM_SCOPE_ONLY
468 		_thr_scope_system = 1;
469 #else
470 		if (getenv("LIBPTHREAD_SYSTEM_SCOPE") != NULL)
471 			_thr_scope_system = 1;
472 		else if (getenv("LIBPTHREAD_PROCESS_SCOPE") != NULL)
473 			_thr_scope_system = -1;
474 #endif
475 	}
476 	init_once = 1;
477 }
478